linux-kernel - Re: [PATCH v2 3/8] usb: dwc3: make controller clear transfer resources after complete

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Date:   Wed, 5 Sep 2018 05:38:38 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Anurag Kumar Vulisha <anurag.kumar.vulisha@...inx.com>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "v.anuragkumar@...il.com" <v.anuragkumar@...il.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/8] usb: dwc3: make controller clear transfer
 resources after complete

On 8/17/2018 5:26 AM, Anurag Kumar Vulisha wrote:
> To start transfer with another stream id, controller needs to free
> previously allocated transfer resource. This will be automatically
> done by the controller at the time of XferComplete Event. This
> patch updates the code to issue XferComplete event once all transfers
> are done by setting LST bit in the ctrl field of the last TRB.
>
> Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@...inx.com>
> ---
>  Changes in v2:
> 	1. None
> ---
>  drivers/usb/dwc3/gadget.c | 19 ++++++++++++++++---
>  1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index efc6e13..b3e9e7f 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -571,7 +571,8 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
>  
>  	if (usb_ss_max_streams(comp_desc) && usb_endpoint_xfer_bulk(desc)) {
>  		params.param1 |= DWC3_DEPCFG_STREAM_CAPABLE
> -			| DWC3_DEPCFG_STREAM_EVENT_EN;
> +			| DWC3_DEPCFG_STREAM_EVENT_EN
> +			| DWC3_DEPCFG_XFER_COMPLETE_EN;
>  		dep->stream_capable = true;
>  	}
>  
> @@ -999,6 +1000,15 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb,
>  	if (chain)
>  		trb->ctrl |= DWC3_TRB_CTRL_CHN;
>  
> +	/*
> +	 * To issue start transfer on another stream, controller need to free
> +	 * previously acquired transfer resource. Setting the LST bit in
> +	 * last TRB makes the controller clear transfer resource for that
> +	 * endpoint, allowing to start another stream on that endpoint.
> +	 */
> +	else if (dep->stream_capable)
> +		trb->ctrl |= DWC3_TRB_CTRL_LST;
> +
>  	if (usb_endpoint_xfer_bulk(dep->endpoint.desc) && dep->stream_capable)
>  		trb->ctrl |= DWC3_TRB_CTRL_SID_SOFN(stream_id);
>  
> @@ -2268,7 +2278,7 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
>  	if (event->status & DEPEVT_STATUS_SHORT && !chain)
>  		return 1;
>  
> -	if (event->status & DEPEVT_STATUS_IOC)
> +	if (event->status & (DEPEVT_STATUS_IOC | DEPEVT_STATUS_LST))
>  		return 1;
>  
>  	return 0;
> @@ -2457,6 +2467,10 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
>  	}
>  
>  	switch (event->endpoint_event) {
> +	case DWC3_DEPEVT_XFERCOMPLETE:
> +		if (!dep->stream_capable)
> +			break;
> +		dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
 Add this:  /* Falls Through */
>  	case DWC3_DEPEVT_XFERINPROGRESS:
>  		dwc3_gadget_endpoint_transfer_in_progress(dep, event);
>  		break;
> @@ -2472,7 +2486,6 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
>  		}
>  		break;
>  	case DWC3_DEPEVT_STREAMEVT:
> -	case DWC3_DEPEVT_XFERCOMPLETE:
>  	case DWC3_DEPEVT_RXTXFIFOEVT:
>  		break;
>  	}

Thinh